1. Field of the Invention
The present invention relates to an arrangement for shutting off an inverter which feeds at least one lamp circuit having a discharge lamp and heatable electrodes, the inverter comprising a bistable shutoff device which flips into the disconnected condition and shuts off the inverter when the integral of the current in a lamp circuit reaches a shut-off limit value and which is held in the disconnect condition dependent on a monitoring current in a monitoring circuit and which flips back to its normal condition when the holding current flowing thereover falls below a flyback limit value, and in which a series connection of a respective electrode of each lamp is provided in the monitoring circuit.
2. Description of the Prior Art
An arrangement of the type described above is disclosed in the International Patent Application PCT/DE 82/00155 and has the advantage that the shut-off of the inverter triggered by a malfunction is canceled when the faulty lamp is removed, i.e. a separate power system disconnect is not required. However, the monitoring circuit must thereby be dimensioned such that the minimum holding current required for the lowest feed voltage under consideration can flow thereacross, the minimum holding current lying above the flyback limit value at which the shut-off device is reset into the normal condition.
During normal operation, though, this holding current causes additional losses that are of particular significance when a resistor of the monitoring circuit is connected in parallel to the oscillating capacitor of the inverter.